def sum_pairs(ints, s):
    res = None
    lens = len(ints)
    start = 0
    while start < lens:
        val2 = s - ints[start]
        print(lens)
        if ints.count(val2) and (ints.index(val2) < lens):
            lens = ints.index(val2)
            res = val2
        start += 1
    return None if res == None else [s - res, res]
arr = [1, -2, 3, 0, -6, 1]
print(sum_pairs(arr, 3))